Such molecular sieves are known in the art. International Application Publication No. WO 93/01884 (WO 93/01884) discloses a hydroprocessing catalyst containing a support material comprising an ultra-large pore crystalline material (molecular sieve) of high surface area and porosity. The crystalline material exhibits after calcination an X-ray diffraction pattern with at least one peak having a relative intensity of 100 at a d-spacing greater than 1.8 nm and having a benzene sorption capacity greater than 15 grams benzene per 100 grams of the material at 6.7 kPa and 25.degree. C.
The crystalline material is typically prepared by crystallization from a starting mixture at strong basic conditions, that is a pH in the range of from 9 to 14. In particular, if the starting mixture does not contain bivalent or pentavalent species it is stated that it is essential to maintain the pH within this range in three out of four synthesis procedures disclosed in WO 93/01884.
The fourth synthesis procedure disclosed in WO 93/01884 should be carried out at a pH of less than 12. In this fourth procedure the same synthesis mixture is to be employed as disclosed with respect to the third synthesis procedure. The lower limit of the pH range which can be used in the fourth procedure is therefore about 9.
Beck et al. (J. Am. Chem Soc. 1992, Vol. 114, pages 10834-10843) discuss the influence of organic templates on the structure and properties of the crystalline material and propose two theoretical models for formation of the crystalline material.
Monnier et al. (Science 1993, Vol. 261, pages 1299-1303) synthesized the crystalline materials at a range of experimental conditions and on the basis of the known experimental results developed a refined model of the formation process which could explain the then known experimental data and which could predict conditions needed for the synthesis of desired structures. According to this publication a pH of at least 9.5 seems essential in order to be able to directly synthesize the crystalline materials. According to Monnier et al. the crystal structure of a monoclinic, layered crystalline material produced in the initial stages of the synthesis process at a pH of at least 9.5 can be altered to a hexagonal crystalline material by a hydrothermal treatment at 373 K at a pH of 7 over 10 days.
It has now been found possible to directly synthesize crystalline material, hereinafter called molecular sieves, as described in WO 93/01884 under acidic, neutral or weak basic conditions, by using starting mixtures containing a fluorine source.